Marine pests

Page Content

If you are heading into the waters of Fiordland, please be aware a Controlled Area notice has been issued for an area of Breaksea Sound to prevent further spread of the Asian seaweed Undaria pinnatifida (Undaria). You may still access the area, however there are some restrictions in place for mooring, equipment and anchoring.

A number of marine pests are found throughout New Zealand waters. These species are easily spread via hull fouling and ballast water, and have the potential to damage underwater ecology, fisheries and aquaculture.

We classify nine marine organisms as pests in the Regional Pest Management Strategy– immediate threats to Southland include Undaria, the Mediterranean Fanworm, and the Clubbed Tunicate.

To date, only one marine pest species has made its way to Southland's coastal waters – the Japanese seaweed Undaria pinnatifida. However, in ports as close as Dunedin, a number of other marine pests are present that could harm our marine environment and industries.

Undaria (Undaria pinnatifida)

Undaria is opportunistic invasive seaweed that forms dense stands underwater, giving it the potential to compete for light and space with native species. Due to Undaria's ability to rapidly spread in the marine environment it is often referred to as the gorse of the sea.

Undaria is native to Japan where it is grown for human consumption. Itlooks similar to Ecklonia, a native species, however mature Undaria plants which can grow 1-2 meters tall are characterised by a distinct mid-rib. It's a highly invasive seaweed found in many major ports throughout the world, including Bluff Harbour here in Southland.

In April 2010, Undaria was found on a mooring line in the remote Sunday Cove in Breaksea Sound, Fiordland. A joint-agency response involving Environment Southland, Ministry for Primary Industries and the Department of Conservation was initiated to attempt eradication of Undaria from Fiordland.

Mediterranean fanworm (Sabella spallanzanii)

Mediterranean fanworm
is a segmented worm that lives within a tube attached to hard substrate.
This species of fanworm can grow to 40cm tall and has a singular fan,
whereas natives have two fans.

Mediterranean fanworm forms dense colonies and can impact native species by competing for food and space. Recent scientific studies indicate that this fanworm can negatively affect the new generation of some marine species and change nutrient flow.

Mediterranean fanworm is established in Whangarei, Waitemata and Lytellton Harbours. Isolated cases have occurred in popular ports and harbours in Northland, Coromandel, Tauranga, Picton and Nelson. Continued efforts focus on restricting the spread of Mediterranean fanworm within New Zealand.

The clubbed tunicate (Styela clava)

Styela clava is a club shaped sea squirt with tough leathery skin. It is cylindrical in shape, grows up to 16cm in length, brown in colour, and has a stalk-like holdfast that anchors the animal to structures such as rocks, wharfs and boat hulls. Styela clava has two siphons on the top of the organism which it uses to filter food from its surrounding environment.

Styela clava is
of major concern to New Zealand's aquaculture industry. This species of
tunicate has the ability to foul aquaculture gear such as mussel lines,
smothering and competing for space and food with farmed species.

What we're doing

Undaria response

In Fiordland, Undaria is restricted to Sunday Cove. Monthly dive inspections at high-use sites (berthing areas) throughout Fiordland are undertaken by Environment Southland staff in partnership with the Ministry of Primary Industries and the Department of Conservation.

The aim of the programme is to detect any plants before they have the opportunity to reach reproductive maturity. If new plants are found, they are measured, the location is recorded and the plants are removed and destroyed. Additionally, sites across Fiordland that are visited regularly by commercial and recreational vessels are surveyed by divers annually.

Fiordland Marine Regional Pathway Management Plan

The Fiordland Marine Regional
Pathway Management Plan was formally adopted on 5 April 2017. It was the first
of its kind in New Zealand and aims to protect one of New Zealand’s most unique
and nationally significant areas from marine pests being carried in on local
and visiting vessels.

With its breathtaking scenery and pristine waters, Fiordland plays an important
role, both ecologically and economically and it is vital we protect it.

The Plan incorporates rules for
clean vessels including clean hull, clean gear, and residual seawater standards
which will apply to vessels of all sizes
entering the area. It also includes a Fiordland Clean Vessel Pass which will
ensure vessel owners/operators are aware of the risks and the ways they can
minimise them.

The plan has been developed and will be
implemented by a partnership group including Environment Southland, Fiordland
Marine Guardians, Ministry for Primary Industries, Department of Conservation,
and Ngāi Tahu.